Ionics Instruments 2004 Page 10-6 DLM 30007-08 Rev. A
Compare the color of the paper with the pH color scale on the side of the pH
paper container. If the pH is not < 2, not enough acid is being added to the
sample stream. Possible reasons for high pH include:
Acid flow rate is too low; check acid flow rate from the SETUP menu and
increase flow rate if necessary.
Acid reservoir is empty or low; check Error Stack, Error #12.
Acid syringe is broken or not working; contact Ionics Instruments for
instructions.
Mininert valve on the acid reservoir is closed.
Oxidizer Flow Rate Too High
If the oxidizer flow rate is too high, the excess reagent will decompose and
form oxygen bubbles in the analyzer and give erratic TOC measurements. In
most cases, the gas bubbles can be seen in the outlet line. If readings are
erratic and bubbles can be observed in the outlet line, decrease the oxidizer
flow rate from the REAGENTS menu. This problem may occur just after the
oxidizer reservoir has been changed and fresh oxidizer is in the analyzer.
Some trial and error is required for adjusting the oxidizer flow rate. One
procedure is to reduce the flow rate in 0.5 µL/min. increments, wait
approximately 20 min and check whether the gas bubbles in the analyzer
outlet line have disappeared. If the bubbles persist, decrease the oxidizer flow
an additional 0.5 µL/min., repeating this procedure until readings are stable.
Oxidizer Flow Rate Too Low
For water samples containing > 1 ppm TOC, the oxidizer flow rate must be set
to add enough reagent to completely oxidize the organic compounds. If the
flow rate is too low, only partial oxidation will occur and low TOC values will be
obtained. Check the oxidizer flow rate from the SETUP menu and the
recommended oxidizer flow rates in Table 2 in the Installation chapter. If the
flow rate is lower than the recommended flow rates, increase the oxidizer flow
rate.
If the flow rate is set to the recommended value, the water sample may
contain organic compounds that are particularly difficult to oxidize and may
require additional persulfate oxidizer. Again, some trial and error is required to
find the best oxidizer flow rate. Try increasing the flow rate by 0.5 µL/min. and
monitor the TOC and check for gas bubbles in the analyzer outlet line. If the
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